JPS6020048A - Heat exchanger - Google Patents

Abstract

PURPOSE:To prevent the heating surface of a heat transfer part from being corroded by condensate, by forming a double coating layer on the surface, by coating a compound of heat- resistant polymer, with which an ingredient such as flaky filler is dispersedly mixed, on the clear coating layer of heat-resistant polymer. CONSTITUTION:A double coating layer is coated on the heating surface 4 of a heat transfer part which is made of copper as a matrix metal. The double coating layer is composed by coating a compound of heat-resistant polymer with which an ingredient such as flaky filler is dispersedly mixed, on the clear coating layer of heat-resistant polymer. The surface 4 is subjected to heat, steam, and acid condensate in which combustion gas is dissolved, but it can be prevented from being corroded by heightening the resistances to heat and acids by coating a double coating layer on it. That is, thermal and chemical resistances can be largely increased in the top coating layer 6 by dispersedly mixing the filler ingredient with the heat-resistant polymer, while the clear coating layer 5 maintains the original density of the coating layer 6 by preventing the layer 6 from becoming porous quality by the effects of heat and acidification. Plurality of filler ingredients are used for the layer 6, and one of them is to be a flaky substance in order to fill the pin holes that may grow in the layer, to prevent it from steam and oxygen coming into it, and to decrease the effect of combustion flames received on it.

Description

DETAILED DESCRIPTION OF THE INVENTION The industrial field of application "Fv" relates to heat exchangers made of copper heat transfer members used in instant water heaters, hot water heaters, space heaters, etc.

Structure of a conventional example and its problems FIG. 1 shows a heat exchanger used in a conventional instantaneous water heater. As shown in the figure, the heat exchanger consists of a drum 1 installed inside the entire combustion chamber and a heat exchange chamber 2 through which water to be heat exchanged passes.
The heat-transfer part of the heat-absorbing fin 3 provided in one part of the drum 1 is made of copper, and the surface of this heat-transfer part is plated with molten metal mainly containing lead. There is.

With this configuration, on the combustion exhaust gas contact side, especially in low temperature areas such as the contact area between the drum 1 and the heat exchanger chip 2, or the contact area between the heat absorption fins 3 and the heat exchanger chip 2, there is a There is a problem in that the contained NOx, 5OxC, CO2, water vapor, etc. condense and turn into acids, corroding molten metal plating and copper, which is the base metal.

Such corrosion produces a large amount of corrosion products such as lead carbonate, lead nitrate, basic lead carbonate, and patina, and these corrosion products accumulate on the heat absorption fins 3 and obstruct the flow of exhaust gas, resulting in incomplete may cause combustion or significantly reduce heat exchange efficiency.
As it gets wet, it peels off and falls off in powder form.
It was not sanitary either, as the hot water heater contaminated the surrounding area.

Further, problems such as holes being formed in the drum 1 and the heat absorbing fins 3 occur due to the progress of corrosion, so it is not desirable for safety.

OBJECT OF THE INVENTION The present invention overcomes these conventional drawbacks, and includes:
Combustion U1: Preventing corrosion of the heat exchanger due to acidic condensed water with dissolved scum and improving the corrosion resistance and durability reliability of the heat exchanger.
The purpose is to achieve e.

Structure of the Invention To achieve this object, the present invention provides that the surface of a heat transfer member made of copper as a base metal is composed of two coach ink layers of a heat-resistant polymer, and the undercoat is a heat-resistant polymer. On the surface of this clear layer,
A paint made by dispersing and mixing multiple fillers with a solvent in a heat-resistant polymer, and one of the fillers listed in IJ is in the form of flakes, and is applied to form a 1-tub coat layer. .

This configuration completely prevents high-temperature oxidation of the base metal and attack by acidic condensed water, and also prevents incomplete combustion caused by corrosion, low heat exchange efficiency, or scattering of corrosion products and droplets due to F. It can also prevent contamination.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will now be described with reference to FIG. A clear coating layer 5 without any addition of heat-resistant polymer is provided, and the surface of the clear coating layer 5 is further filled with a plurality of fillers in the heat-resistant polymer. B is dispersed together with a solvent, and one of the paints is filled with flakes +tc to form a top coat coating film). In the coating layer 6, the flaky fillers C are arranged like leaves on the surface of the coating, and the fillers A and B are uniformly dispersed and mixed in the coating.

In this configuration, when the gas burner (not shown) disposed in the combustion chamber F section in the drum 1 of the heat exchanger shown in FIG.
The water flowing through them is partially cooled and condenses on these surfaces. NOx contained in the combustion exhaust case. SOx
, C○. CO2 and other substances are dissolved and filtered, making it highly corrosive.
For example, it becomes acidic condensation water such as HNO3. Furthermore, in terms of temperature, the fin tip of the heat-absorbing fin 3 is heated to a high temperature of 250° C. or higher.

The heat exchanger is subject to thermal attack due to heat, acidic condensation water, water vapor, etc., but the coating layer 5.6 provides heat resistance and
It has significantly improved acid resistance and can completely prevent this type of corrosion.

Although dispersing and mixing a filler into a heat-resistant polymer significantly improves the thermal and chemical properties of the heat-resistant polymer itself, when a single coat is formed, the coated film becomes porous and the matrix is There is a concern that high-temperature oxidation of raw metals cannot be prevented. However, in the present invention, since five clear coating layers of heat-resistant polymer are formed, the original denseness of the coating film is not impaired, and the adhesion due to the oxidation of the base metal copper is maintained. There are no low scores.

The clear coating layer 5, which is the undercoat layer, prevents oxidation of the matrix and prevents corrosion-causing substances from entering the coating, and the topcoat layer, which is the coating layer 6 in which fillers are dispersed, provides heat resistance. , acid resistance, steam resistance, etc. can be significantly improved, and reliability as a combustion device can be improved.

The heat-resistant polymer used in the present invention is not particularly limited, but it has been confirmed that the heat-resistant temperature of the polymer itself can be increased by about 100°C by selecting an appropriate filler and its addition amount. From this point of view, silicon-based, polyimide-based, polyamide-imide-based, SiC polymer-based, inorganic polymer-based, and organic titanate-based polymers are preferable.

In addition, as a filling material, it is suitable for improving thermal conductivity, heat resistance, acid resistance, etc. At. Examples include metal powder including Cu, graphite, alumina powder, tetrafluoroethylene resin, SiC powder, and metal oxide powder, and it is better to use a plurality of them, preferably a combination of two or more. One type of filler is a flake-shaped filling (using special techniques) to block pinholes in the paint film to prevent oxygen and water vapor from entering, and to reduce the effects of flames and increase the heat resistance reliability of the paint film. It is better.

Leaf ink type At powder was used as the flaky filling material, and 4) ethylene chloride powder and C' were used as the filling material.
The best results are obtained when a combination of powders such as U, AL, and graphite are used.

In this case, leafing-type AA is used to improve heat resistance, and by dispersing tetrafluoroethylene powder into the network structure of the base heat-resistant polymer, acid resistance and steam resistance are significantly improved. Thermal conductivity can also be improved by adding metal powder such as A or 4.

Furthermore, the amount of filler added should be 50 wt% or more in total, based on the solid content (heated residue) of the heat-resistant polymer.
(preferably 60 to 75 wt%), of which the amount of flaky filler added is preferably 1/2 or more.

As described in [11J], the flake-like fillers are effectively arranged in a leaf pattern on the surface layer of the coating film, and the other fillers H' are uniformly dispersed within the network structure of the heat-resistant polymer. This is to form a coating film (film formation).

Effects of the Invention As described above, the present invention provides the surface of a heat transfer part made of copper as a base metal with properties such as prevention of oxidation of the base metal, adhesion with copper, compactness,
A clear coach ink layer that serves as an undercoat made of a heat-resistant polymer with excellent corrosion resistance, and a top that has a filler dispersed in a heat-resistant polymer with excellent heat resistance, acid resistance, steam resistance, and thermal conductivity. Since a single coating layer is formed, there is no corrosion of the heat exchanger, and the durability and reliability are greatly improved.Therefore, the accumulation, scattering, and falling of corrosion products on the heat-absorbing fins are prevented. There is no concern for incomplete combustion or hygiene.

Furthermore, it is possible to improve heat exchange efficiency.

Furthermore, in the present invention, since both the undercoat and topcoat are made of the same base heat-resistant polymer, the processing process does not require two firings as in the conventional method, but can be done in one firing, making it economical and conventional. Its monthly value is extremely high.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a heat exchanger for an instant water heater, and FIG. 2 is a sectional view of a main part showing an embodiment of the heat exchanger of the present invention. 4... Copper heat transfer member, 5... Undercoat layer, 6... Totufu+-1-m. Name of one substitute Patent attorney Toshio Nakao and one other person Figure 1

Claims (1)

[Claims] The surface of the heat transfer part made of copper as the material metal is composed of two coating layers of heat-resistant polymer, and the undercoat of the coating layer is formed of a clear layer of heat-resistant polymer. A top coat is formed on the clear layer using a paint in which a plurality of heat-resistant fillers are dispersed in the heat-resistant polymer together with a solvent, and one of the fillers listed in nIJ is in the form of flakes. heat exchange k.